Cyanoethylation and xanthation of alkali cellulose



United States Patent 3,146,116 CYANOETHYLATION AND XANTHATION OF ALKALI CELLULOSE Arthur I. Bates, Wilmington, Del., assignor, by mesne assignments, to FMC Corporation, San Jose, Calif., a

corporation of Delaware No Drawing. Filed Sept. 29, 1960, Ser. No. 59,191 7 Claims. (Cl. 106-165) This invention relates to a process for producing a modified viscose having improved properties. More particularly it relates to the simultaneous cyanoethylation and xanthantion of alkali cellulose.

The usual method for cyanoethylating cellulose involves treating an alkaline suspension of cellulose with acrylonitrile dissolved in the alkaline solution. This procedure uses comparatively large amounts of acrylonitrile and results in waste liquors which must be subjected to recovery treatments to reduce acrylonitrile and alkali losses. Viscose has been cyanoethylated by adding acrylonitrile directly to viscose. However, large amounts of acrylonitrile are consumed by the by-product sulfur compounds present in the viscose.

It is an object of this invention to provide a viscose material having an accelerated aging rate.

It is another object of this invention to provide cyanoethylated viscose produced with less acrylonitrile than that previously produced.

It is a further object of this invention to provide a method for cyanoethylating alkali cellulose which uses less acrylonitrile and eliminates the necessity for recovery treatments of Waste liquors.

It is still another object of this invention to provide a method for the production of cellulose articles having improved properties such as luster and clarity.

It is a still further object of this invention to provide a method for the production of cellulose fibers having improved extensibility and a smoother cross section, together with increased dye affinity.

It is a still further object of this invention to provide soluble regenerated viscose fibers with considerable reduction in the amount of carbon bisulfide used for xanthating.

These and other objects are accomplished in accordance with the present invention which broadly includes a method for preparing a modified viscose which comprises reacting alkali cellulose with from 01% to 60%, based on the weight of the cellulose, of acrylonitrile and from 20 to 60% based on the weight of the cellulose, of carbon bisulfide, and dissolving the reacted cellulose in a dilute alkali solution. It is preferred, for a viscose used for spinning hydrophobic fibers, that less than 1% acrylonitrile be used with from 25 to 35% carbon bisulfide. However, for a process wherein the amount of carbon bisulfide used for xanthating the alkali cellulose is advantageously reduced, large amounts of acrylonitrile, up to about 60%, can be used to replace much of the carbon bisulfide. Regenerated articles formed from viscose prepared with large amounts of acrylonitrile are highly water-soluble.

It is theorized that the acrylonitrile reacts with the cellulose to form cyanoethylated cellulose; this swells the material and lets the carbon bisulfide in between the cellulose chains so that it reacts or xanthates faster.

This invention also includes a method of forming shaped cellulosic articles by first preparing a modified viscose as described above, forming the viscose into a shaped article, and then regenerating the viscose to produce the finished article. In the formation of cellulosic fibers from the cyanoethylated viscose, the viscose should be prepared with less than 1% acrylonitrile based on the cellulose. This viscose can be spun into filaments which are stretched to from 25 to 75% of their original length. The stretched ice fibers are then hot water washed in a relaxed state and dried to produce excellent crimped fibers.

The following is an example demonstrating the method of preparing a modified viscose and the method of producing fibers from the viscose.

Example I Alkali cellulose is charged as usual into a churn used for xan thation. Carbon bisulfide containing a predetermined amount of acrylonitrile is added to the churn to yield 30% carbon bisulfide and .25% acrylonitrile based on the weight of cellulose in the alkali crumbs. After simultaneously xanthating and cyanoethylating the alkali crumbs for a period of 1 /2 hours, the reacted cellulose is dissolving in dilute sodium hydroxide to form a viscose containing 8.6% cellulose and 6.4% sodium hydroxide.

This viscose was used to spin 15 denier per filament fibers from a coagulating and regenerating bath containing 7.2% sulfuric acid; 1% Zinc sulfate and 20% sodium sulfate at 50 C. bath temperature, using a spinning speed of meters per minute and a bath immersion of 32 inches. After leaving the bath the filaments in the form of a fiber were stretched 40% of their original length, then relaxed in hot water, where the fibers developed an excellent crimp. The extensibility of the finished fiber produced by this method is considerably higher than that produced in a similar manner from viscose prepared from a non-cyanoethylated cellulose xanthate. Other properties such as cross section, water retention and dye affini-ty are also modified.

A modified viscose produced in the same manner as described above but aged for 48 hours produced a fiber having a still better crimp and improved luster. Generally fibers produced with the modified viscose had a firmer hand, better crimp, more luster and a less milky appearance than fiber spun with conventional viscose. The improved fiber also had greater soil resistance and its crush recovery was almost 10% greater than the conventional fiber.

Example II A viscose solution was prepared by reacting alkali cellulose prepared as described in Example I with 24%, based on the weight of the cellulose, of carbon bisulfide and 60%, based on the weight of cellulose, of acrylonitrile. A yarn was spun from this viscose which swelled greatly in water.

Trial viscoses were prepared by reacting alkali cellulose with various mixtures of acrylonitrile and carbon bisul fide where the amounts of the acrylonitrile component varied from 60% down to 076%, based on the weight of the cellulose, and the amount of carbon bisulfide was maintained at 30%. Acrylonitrile, even at .076% accelerated the aging of the viscose greatly as determined by the sodium chcloride salt test. For higher concentrations of acrylonitrile the strength and extensibility of spun yarn produced therewith is lowered. Thus, for carpet fibers and the like, viscose prepared with the smaller percentages of acrylonitrile is preferred.

Various changes and modifications may be made in practicing the invention without departing from the spirit and scope thereof and, therefore, the invention is not to be limited except as defined in the appended claims.

I claim:

1. A method for preparing a modified viscose which comprises reacting alkali cellulose with a mixture containing from 0.01 to 60% of acrylonitrile and from 20 to 60% of carbon bisulfide, said percentage amounts being based on the weight of the cellulose, and dissolving the reacted cellulose in a dilute aqueous solution of alkali hydroxide.

2. The method of claim 1 wherein less than 1% acrylonitrile is used.

3. The method of claim 1 wherein over 1% acrylonitrile is used.

4. A method of forming shaped cellulosic articles which comprises reacting alkali cellulose with a mixture containing from 0.01 to 60% of acrylonitrile and from 20 to 60% of carbon bisulfide, said percentage amounts based on the weight of the cellulose, dissolving the reacted cellulose in dilute alkali to form viscose, forming the viscose into a shaped article, and regenerating the viscose article.

5. A method of forming shaped cellulosic articles which comprises reacting alkali cellulose with a mixture containing from 0.01 to 1% of acrylonitrile and from 25 to 35% of carbon bisulfide, said percentage amounts based on the weight of the cellulose, dissolving the reacted cellulose in dilute alkali to form viscose, forming the viscose into a 15 shaped article, and regenerating the viscose article.

5 relaxed in hot water and dried.

References Cited in the file of this patent UNITED STATES PATENTS Lilienfeld Feb. 16, 1943 Houtz May 15, 1945 OTHER REFERENCES Somers: British Rayon and Silk Journal, volume 26, No. 312, May 1950, page 62.

MacGregor: J. Soc. Dyers and Colorists, vol. 67 (1951), page 68.

Disclaimer 3,146,116.-Art7m1- I Bel ates, Wilmington, Del. CYANOETHYLATION AND XANTHATION OF ALKALI CELLULOSE. Patent dated Aug. 25, 1964. Disclaimer filed May 22, 1969, by the assignee FM 0 001790- ratio n. Hereby enters this disclaimer to claims 1, 3 and l of said patent.

[Ofieial Gazette December 30, 1.969.] 

5. A METHOD OF FORMING SHAPED CELLULOSIC ARTICLES WHICH COMPRISES REACTING ALKALI CELLULOSE WITH A MIXTURE CONTAINING FROM 0.01 TO 1% OF ACRYLONITRILE AND FROM 25 TO 35% OF CARBON BISULFIDE, SAID PERCENTAGE AMOUNTS BASED ON THE WEIGHT OF THE CELLULOSE, DISSOLVING THE REACTED CELLULOSE IN DILUTE ALKALI TO FORM VISCOSE, FORMING THE VISCOSE INTO A SHAPED ARTICLE, AND REGENERATING THE VISCOSE ARTICLE. 